The present invention relates to a vibration pick-up with a pressure sleeve.
Vibration pick-ups with pressure sleeves are known in the art. One of such vibration pick-ups is disclosed for example in the German Patent Document DE-OS 44 03 660. The vibration pickup with the pressure sleeve of this reference is used for knocking sensors in internal combustion engines. The vibration pick-up is mounted fixedly through a mounting region on the component whose vibrations must be detected. The vibrations to be detected are knocking noises of the internal combustion engine during the operation, which are transmitted through the pressure sleeve to a piezo-ceramic detector and converted into an evaluatable output signal of a vibration pick-up operating as a knocking sensor. The type of placing or clamping the detector in the pressure sleeve and the mounting on the vibrating component has a great influence both on the manufacturing process as well as on the eventual error measurements and disturbances in the connected evaluating circuit during the operation.
The known pressure sleeves of the vibration pick-ups are composed, as a rule, of a very resistant and hard material such as for example steel to withstand the relatively high pressure and temperature fluctuations to provide correct measurements. The housing accommodating the pressure sleeve and the detector together with its clamping means is composed as a rule of a synthetic plastic material, such as for example polyurethane (PUR) or glass-fiber-rainforest polyamide (PA66 GF35). It is known from the European Patent Document EP 0 211 019 B1 to connect these parts firmly with one another by correspondingly designed threaded constructions and in some cases through seal labyrinths so that these connections are not substantially affected by temperature actions.